The present invention relates to methods of controlling enzymatic decomposition of peroxide, and, particularly, methods for controlling enzymatic decomposition of peroxide in bleaching treatments of cellulose pulp, and paper products of these methods.
Hydrogen peroxide is widely used in industrial and domestic applications. Hydrogen peroxide is extensively used, for example, in the production of pulp, such as in the production of recycled pulp, to enhance pulp and paper brightness by bleaching. Hydrogen peroxide, however, is readily decomposed in the presence of certain enzymes, such as catalase, present in water from processing recycled paper or other organic matters. In paper recycling mills, for example, mill pulp slurries and white water can harbor microorganisms, which produce enzymes that can catalyze the decomposition of hydrogen peroxide. The hydrogen peroxide treatment, as a result, can become hampered and bleaching effectiveness is reduced. For example, one of these enzymes, catalase, can rapidly catalyze the decomposition of hydrogen peroxide into oxygen and water. It has been reported that one catalase molecule can decompose 40,000 peroxide molecules at 0° C. in one second (the Encl. of Biochemistry, Roger J. Willams, et al., eds., page 634). As a result, increased dosages of hydrogen peroxide must be added in efforts to offset peroxide losses to enzymatic decomposition and achieve the desired brightness in the product. Previous efforts have been attempted for inhibiting catalase activity in the presence of hydrogen peroxide.
U.S. Pat. No. 5,728,263 relates to a method of inhibiting enzymatic decomposition of peroxide that involves producing and treating recycled fiber pulp and other fiber pulp with peroxide, wherein free dialdehydes, such as glutaraldehydes, and acetals thereof are included to inhibit enzymatic decomposition of the peroxide. The amount of the dialdehyde or acetal used for the production of recycled fiber pulp or other fiber pulp can be 0.05 to 2 kg per ton of produced fiber pulp based on dry weight.
WO 2005/001056 A2 relates to a method for controlling a catalase contamination that involves contacting a composition comprising catalase activity and/or a composition comprising a catalase producing microorganism with a protease in an amount effective to reduce catalase activity in the composition and/or to prevent an increase in catalase activity in the composition.
WO 2006/032450 A1 relates to the use of HCHO-releasing chemicals for the inactivation of enzymes, wherein the enzyme is catalase, amylase, protease, or cellulose. Examples of the HCHO-releasing chemicals are 1,3,5-tris-(2-hydroxyethyl)-1,3,5-hexahydrotriazine (HT) and imidazo[4,5-d]imidazol-2,5-(1H, 3H)-dione-tetrahydro-1,3,4,6-tetrakis-(hydroxymethyl) (TD).
U.S. Pat. No. 6,432,262 B1 relates to a method of stabilizing hydrogen peroxide in an aqueous solution, such as a circulating water slurry, which involves adding an aldehyde donor, such as a methylolhydantoin, to the solution (or slurry). U.S. Pat. No. 6,432,262 B1 states that suitable aldehyde donors include, but are not limited to, imidazolidinyl urea, Quaternium-15, diazolidinyl urea, bromonitropropanediol, methenamine, 5-bromo-5-nitro-1,3-dioxane, sodium hydroxymethyl-glycinate, 3,5-dimethyl-1,3,5,2H-tetrahydrothiadiazine-2-thione,hexahydro-1,3,5-tris(2-hydroxyethyl)triazine, hexahydro-1,3,5-triethyl-s-triazine, polymethoxy bicyclic oxazolidine, tetrakis(hydroxymethyl) phosphonium sulfate, methylolhydantoins, and any combination of any of the foregoing. This patent further states that preferred aldehyde donors include, but are not limited to, methylolhydantoins, such as monomethyloldimethylhydantoins (MMDMHs), dimethyloldimethylhydantoins (DMDMHs), and any combination of any of the foregoing. Examples of methylolhydantoins include, but are not limited to, 1-hydroxymethyl-5,5-dimethylhydantoin (a MMDMH), 3-hydroxymethyl-5,5-dimethylhydantoin (a MMDMH), and 1,3-bis(hydroxymethyl)-5,5-dimethylhydantoin (DMDMH) mixtures.
U.S. Pat. No. 5,885,412 relates to a method and composition for suppressing or inhibiting the decomposing action of enzymes on hydrogen peroxide, e.g. peroxidase and catalase, during bleaching of cellulose fibers with hydrogen peroxide, especially in connection with the production of recycled paper, in such a way that microorganisms are not markedly affected, and discharges that are dangerous to the environment are minimized. The composition contains hydroxylamine, thiocyanate salts, formic acid, ascorbic acid or nitrites.
GB 2269191 A relates to a process for treating aqueous process liquors, e.g., in waste paper recycling, which contains catalase positive microorganisms and reducing the rate of hydrogen peroxide decomposition by catalase which employs an organic peracid as a biocide with the process liquor at acidic or neutral pH.